1. Field of the Invention
The present invention relates to a voice message service method for a multimedia internet protocol system, and in particular to a voice message service method for a multimedia internet protocol system which can transmit/receive voice packet data having different encoding methods through one server.
2. Description of the Background Art
In a state where a user is not able to answer the phone, if the phone rings, a voice message service serves to answer the phone, store a voice message, and transmit the voice message when the user wants. The voice message service is provided to most of communication products from wire and wireless telephones to mobile phones. In addition, the voice message service is supplied to an internet phone (IP phone) which transmits a voice in an intranet environment or a local area network LAN in an internet environment.
On the other hand, various data including a voice, for example an image and/or a text are transmitted through one network in the LAN environment, differently from a telephone network transmitting/receiving a voice having a size of 64 kbps. Accordingly, the encoding techniques are used. In case a transmitting side and a receiving side employ different encoding techniques, it is impossible to transmit/receive the voice. As a result, servers must be provided in accordance with each encoding technique. In addition, the IP phones using the identical encoding technique to the encoding technique used in the servers must be connected to the servers.
The IP phone at the transmitting side encodes and transmits the voice packet data by using the encoding technique. A software which can process the packet data received according to the encoding technique is provided in a voice message service VMS server. The software stores the periodically-received packet data as a file. When the IP phone demands a message detection, the software divides the stored packet data into a certain size, and periodically transmits the divided packet data. The IP phone at the receiving side receives the voice packet data in accordance with each encoding technique. A bandwidth of the voice packet data is dependent upon the encoding techniques.
For convenience""s shake, the G.711 technique and the G.723.1 technique will now be explained as the encoding techniques.
FIG. 1 illustrates devices for performing a conventional voice message service method for a multimedia internet protocol system, and transmission and reception of the voice packet data. A first IP phone, a third IP phone, and a first VMS server employ the G.711 technique, and a second IP phone, a fourth IP phone and a second VMS server utilize the G.723.1 technique. A software processing the G.711 technique is provided to the first VMS server, and a software processing the G.723.1 technique is provided to the second VMS server.
The first IP phone encodes the voice packet data according to the G.711 technique, and transmits the data at a size of 252 bytes per 30 msec. The first VMS server decodes the voice packet data in accordance with the G.711 technique, and stores them as a file. When the third IP phone demands the voice, the first VMS server periodically transmits the stored voice packet data to the third IP phone in accordance with the G.711 technique. Accordingly, the user using the third IP phone receives the voice message from the first IP phone.
The second IP phone encodes the voice packet data in accordance with the G.723.1 technique, and transmits the data at a size of 84 bytes per 90 msec. The second VMS server decodes the data according to the G.723.1 technique, and stores the data as a file. When the fourth IP phone demands the voice, the second VMS server periodically transmits the stored voice packet data to the fourth IP phone in accordance with the G.723.1 technique.
As described above, the voice packet data encoded in accordance with the G.711 technique is compressed and transmitted/received at a size of 252 bytes per 30 msec, and the voice packet data encoded in accordance with the G.723.1 technique is compressed and transmitted/received at a size of 84 bytes per 90 msec. That is, the voice packet data encoded in accordance with the G.711 technique is decoded in accordance with the same technique, and the voice packet data encoded in accordance with the G.723.1 technique is decoded in accordance with the same technique.
Accordingly, in order to utilize the G.711 and G.723.1 techniques, a timer for counting 20 msec, a timer for counting 90 msec, a packet processing variable for processing 252 bytes, and a packet processing variable for processing 84 bytes are necessary. Here, the packet processing variables are required to store the packet data received through a socket, and to decide a data corresponding to a size of the variable.
As shown in FIG. 1, a solid arrow implies that the voice packet data can be transmitted/received between the devices employing the identical encoding technique, and a dotted arrow implies that the voice packet data cannot be transmitted/received between the devices using the different encoding techniques. That is, the encoding technique of the first IP phone is different from that of the second IP phone, and thus the first and third IP phones cannot transmit/receive the voice packet data through the second VMS server. Identically, the second IP phone and the fourth IP phone cannot transmit/receive the voice packet data through the first VMS server.
As a result, the conventional voice message service method has a disadvantage in that the servers as many as the encoding techniques must be provided in order to use various encoding techniques, thereby requiring high price and many devices.
On the other hand, various encoding techniques can be processed through one server in a hardware method. However, in order to respectively process the plurality of encoding techniques, a software must be provided as many as the encoding techniques. That is, a software for processing the G.711 technique and a software for processing the G.723.1 technique are necessary. Accordingly, a work amount of the server and a cost are increased.
It is therefore a primary object of the present invention to provide a voice message service method for a multimedia internet protocol system which can transmit or receive voice messages having different encoding techniques by using one software in one server.
It is another object of the present invention to provide a voice message service method for a multimedia internet protocol system which can transmit or receive voice messages regardless of encoding techniques.
In order to achieve the above-described objects of the present invention, there is provided a voice message service method for a multimedia internet protocol system wherein voice packets received from a transmitting IP phone at a predetermined size and a predetermined period in accordance with each encoding technique are sequentially stored as a file, without performing decoding and encoding operations, and the stored voice packets are sequentially transmitted to a receiving IP phone, when a transmission demand is transmitted from the receiving IP phone by a predetermined period.